<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        li {
            list-style: none;
        }

        #container {
            width: 750px;
            height: 291px;
            margin: 100px auto;
            background: #ccc;
            overflow: hidden;
            position: relative;
        }

        #indicators {
            position: absolute;
            right: 20px;
            bottom: 20px;
        }

        #indicators li {
            float: left;
            width: 20px;
            height: 20px;
            margin-right: 10px;
            background: #000;
            color: #fff;
            text-align: center;
            line-height: 20px;
            cursor: pointer;
        }

        #indicators li.active {
            background: #f00;
        }

        #imgs img {
            display: none;
        }

        #imgs img.active {
            display: block;
        }

        #arrows span {
            width: 40px;
            height: 40px;
            background: rgba(0, 0, 0, 0.6);
            color: #fff;
            text-align: center;
            line-height: 40px;
            position: absolute;
            top: 50%;
            margin-top: -20px;
            cursor: pointer;
        }

        #prew {
            left: 0;
        }

        #next {
            right: 0;
        }
    </style>
</head>

<body>

    <div id="container">
        <ul id="indicators">
            <li class="active" index="0">1</li>
            <li index="1">2</li>
            <li index="2">3</li>
            <li index="3">4</li>
            <li index="4">5</li>
        </ul>
        <div id="imgs">
            <img class="active" src="./imgs/1.jpg" alt="">
            <img src="./imgs/2.jpg" alt="">
            <img src="./imgs/3.jpg" alt="">
            <img src="./imgs/4.jpg" alt="">
            <img src="./imgs/5.jpg" alt="">
        </div>
        <div id="arrows">
            <span id="prev">&lt;</span>
            <span id="next">&gt;</span>
        </div>
    </div>

    <script>
        // let container = document.querySelector('#container')
        let indicatorsUl = document.querySelector('#indicators')
        let indicators = indicatorsUl.children
        let imgs = document.querySelectorAll('#imgs img')
        let prev = document.querySelector('#prev')
        let next = document.querySelector('#next')
        let currIndex = 0



        indicatorsUl.addEventListener('click', e => {
            let target = e.target;
            if (target.tagName === 'LI') {
                let index = target.getAttribute('index');
                currIndex = index;
                changeImg(index);
            }
        }, false);

        prev.onclick = next.onclick = function () {
            if (this == next) {
                currIndex++;
                if (currIndex == imgs.length) {
                    currIndex = 0
                }
            } else {
                currIndex--
                if (currIndex < 0) {
                    currIndex = imgs.length - 1
                }
            }
            changeImg(currIndex)
        }

        function changeImg(index) {
            for (let i = 0; i < indicators.length; i++) {
                indicators[i].className = '';
                imgs[i].className = '';
            }
            indicators[index].className = 'active';
            imgs[index].className = 'active';
        }


        let timer

        function go() {
            timer = setInterval(() => {
                next.onclick()
            },2000)
        }
        go()

        container.addEventListener('mouseover' , () => {
            clearInterval(timer)
        },false)
        container.addEventListener('mouseout' , () => {
            go()
        },false)
    </script>
</body>

</html>